Proper roll crimp on .38 special for a new reloader?

[Wakeman]

Thanks in advance, as I've done a lot of lurking in this forum to gather hints and experience from the experienced reloaders.

I recently loaded my first box of 9mm, and everything went off with out a hitch and functioned great (125gr LRN over 3.4 gr Green Dot).

I'm using the Lee carbide 3 die sets and had no issues with bulged cases or wrinkling.

I'm moving on to .38 special, and I'd like some feedback on how the roll crimp looks. It's a dummy round at the moment, 158gr LSWC. I think I have the Lee bullet seater/crimp die dialed in about right. I'm pretty sure the crimp is centered right at the crimp groove. This will be a light load as well (likely 3.1gr Green Dot), so I don't think I need a monster crimp, but am I on the right path? I'm sorry for the quality of the image, I realize it isn't ideal for this type of inspection.

 

[EddieCoyle]

It looks fine. Don't go any stronger than that.

 

[Wakeman]

Thanks.

Is the degree of crimp independent from the "hotness" of the load? IE, should you just put the same level of crimp on any .38/.357? Or is it something that you should monitor as you shoot? For example, should I only add crimp/increase crimp if I notice my bullets jumping?

Finally, what is a side effect of too much crimping? Is it a potentially dangerous pressure situation? Or is it just working the brass too much, shortening its useful lifetime?

I'm sorry for all the questions, this is one area that they kind of glance over in all of the books I've read. You guys are a wealth of info on most of these subjects.

For the record I'm going to be shooting these loads out of a S&W 36 (no-dash) Chief's Special (around 1973) and a Ruger GP100 ('89). I wanted to go with a lighter bullet for the S&W initially but I wanted to keep the POA/POI the same as they were supposedly setup with 158's in mind. This load should feel like a .22 in the GP100.

 

[EddieCoyle]

You'll be fine with the crimp in the picture on pretty much any revolver round. It's a good strong roll crimp.

The amount of crimp required doesn't really have to change if you have a strong enough crimp to begin with. Some powders (like H110/W296) burn much more consistently with a strong roll crimp.

The downside of too much roll crimp is reduced brass life, bulged cases that won't chamber, driving bands on cast lead bullets ironed flat causing barrel leading, and bad accuracy.

The amount of crimp is not as critical for a low-power cartridge with fast burning powder (like with a .38 Special). It becomes more important when you're loading magnum revolver cartridges - both to reduce the instance of bullet pull, as well as to ensure a consistent burn. The crimp in your picture would be fine even for those.

The easiest way to set your crimp die is to use a factory round. Put it in the press and screw the die down until the die body hits the top of the round. You'll be within 1/2 turn of where you want to be.

If you want to see what too much crimp looks like, lower your die another turn and a half and force a dummy round into it. It will look like this:

See the flattened part of the case at the very top that's been squeezed parallel to the bullet? You don't want that.

 

[Wakeman]

Awesome information. Thanks for the pic too. That will help me (and hopefully others here) as a "too far" reference.